The present invention relates to a method of manufacturing a semiconductor device such as a thin-film transistor or the like to be formed on an insulating substrate, and an apparatus for manufacturing this semiconductor device.
A technique for manufacturing a semiconductor device such as a thin-film transistor (hereinafter to be referred to as a TFT) or the like on an insulating substrate such as glass, quartz or others has been utilized in various kinds of fields such as for application to an active matrix type liquid crystal display unit and others, and attention has been focused on this technique.
In a conventional TFT, amorphous silicon (hereinafter to be referred to as a-Si:H) or the like is uses for an active layer and source and drain electrodes are disposed on this a-Si:H through an ohmic contact layer like n+a-Si:H or others. In recent years, an attempt has been made to use polycrystalline silicon (p-Si) for an active layer in order to have improved mobility to secure sufficient operation speed.
One example of a method of manufacturing this kind of thin-film transistor will be explained below.
For example, a thin film of an amorphous silicon is deposited on a transparent glass substrate to have a desired film thickness by plasma CVD (Chemical Vapor Deposition) method or the like, and this film layer is crystallized by annealing such as ELA (Excimer Laser Annealing) or the like, thereby to form a polycrystalline silicon (p-Si) thin film. Then, after pattering this p-Si thin film, a gate insulating film is deposited on this, and further, a metal film such as an Al alloy or the like is deposited.
A resist pattern is disposed on this metal film, and the metal film is patterned by RIE (Reactive Ion Etching) or the like based on the resist pattern, thereby to form gate electrodes. Then, after removing the resist by ashing, a dopant ion is doped into the p-Si thin film by using the gate electrodes as a mask so as to form source areas and drain areas.
Thereafter, the substrate is heated at 500.degree. C. to activate the doped ion. Then, an inter-layer insulating film is deposited on this, and contact holes are formed by wet etching the gate insulating film and the inter-layer insulating film on the source and drain areas respectively. Then, a drain electrode electrically connected to the drain area and a source electrode electrically connected to the source area are formed respectively to complete a thin-film transistor.
According to the above-described method of manufacturing a thin-film transistor, the respective etching-patterning process, the ion doping process and the activation process are carried out by individual processing units. Accordingly, it requires many expensive individual units and it also takes a long time, for manufacturing a semiconductor device represented by the thin-film transistor. Thus, it has been difficult to sufficiently lower the manufacturing cost.
It has also become clear that unfinished products are stagnated between a plurality of processing units, and this undesirable stagnant brings about adhesion of fine particles and adsorption of water in the atmosphere onto and into the surface of the elements area of the substrate, which causes a reduction in production yield.